Narrative:

On a flight from iad-dfw, approaching linden VOR the VOR signal was a little unstable. Passing the VOR the needle on the HSI wandered a bit then showed us south of the airway (J134). This was about 20 DME. I corrected back to the north and about a min later ZDC called and said we were south of course. I told him that signal was unstable and he gave us a heading to intercept the hvq 079 degree radial (J6). The signal off of hvq was wandering also but not as much as linden. I then had the flight attendants check the cabin for anyone using electronic gear. They found 2 lap top computers in use and had them turned off, which did not help. The hvq signal was still a little weak (150 DME) but was better as we got closer. Navigation was normal for remainder of flight.

Related reports:

Google
 

Original NASA ASRS Text

Title: MLG HAS UNSTABLE SIGNAL FROM VOR AS APCHING. AFTER PASSAGE NEEDLE ON HSI SHOWED S OF COURSE. CORRECTED AS CTLR NOTED NAV ERROR.

Narrative: ON A FLT FROM IAD-DFW, APCHING LINDEN VOR THE VOR SIGNAL WAS A LITTLE UNSTABLE. PASSING THE VOR THE NEEDLE ON THE HSI WANDERED A BIT THEN SHOWED US S OF THE AIRWAY (J134). THIS WAS ABOUT 20 DME. I CORRECTED BACK TO THE N AND ABOUT A MIN LATER ZDC CALLED AND SAID WE WERE S OF COURSE. I TOLD HIM THAT SIGNAL WAS UNSTABLE AND HE GAVE US A HDG TO INTERCEPT THE HVQ 079 DEG RADIAL (J6). THE SIGNAL OFF OF HVQ WAS WANDERING ALSO BUT NOT AS MUCH AS LINDEN. I THEN HAD THE FLT ATTENDANTS CHK THE CABIN FOR ANYONE USING ELECTRONIC GEAR. THEY FOUND 2 LAP TOP COMPUTERS IN USE AND HAD THEM TURNED OFF, WHICH DID NOT HELP. THE HVQ SIGNAL WAS STILL A LITTLE WEAK (150 DME) BUT WAS BETTER AS WE GOT CLOSER. NAV WAS NORMAL FOR REMAINDER OF FLT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.